IEEE Power & Energy Magazine - May/June 2017 - 46

The SAU may reduce the DMS's burden for computation,
data storage, and information exchange, thanks to local data
processing and control. It may also speed up the coordination/optimization of control actions and extend the monitoring and control of the distribution network to every corner of
MV and LV networks, when compared to traditional control
center solutions.
The SAU's database component is the core of data storage related to field measurements, network models, business
models, and algorithm execution. The same database is used
to exchange information among algorithms and interfaces
implemented in the SAU, for the state estimation/forecast,
and for the control and monitoring of the grid connected
to the SAU. The measure and control schema of database
has been defined from IEC 61850 data model. The network
model schema has been designed from the CIM.

Use Cases
Monitoring

In the monitoring system, the SAU is in charge of collecting values, events, and signals from its subnet to monitor the
grid. After an internal elaboration phase, the SAU reports an
aggregated view of the network to the upper level. Measurement and static network data are stored in a local database
with an increased granularity from the underlying grid to
the control center and are maintained only where necessary to locally perform forecasting, estimation, and control
algorithms. State estimation provides system quantities that
are not directly measured. Second, it is needed because real
implementations of monitoring systems are subject to errors
in measurements, due to communication failures, data corruption, or the temporal unavailability of a meter. Load and
production forecasting algorithms are needed for daily and
day-ahead forecasting.
State estimation and forecasting are two advanced functionalities to provide information about a complete network

using incomplete and uncertain information. The distribution
of these functionalities to SAUs is a completely novel idea.
Decentralized advanced functionalities enable the real-time
scalability of monitoring systems, may reduce investment
and operational costs of monitoring systems, and provide a
tool to detect broken or unreliable measurement units.
Decentralized IEC 61850 FLISR Solution

The FLISR application can reduce outage duration and,
therefore, considerably impact the profitability of DSOs. The
distributed FLISR scheme with peer-to-peer communication
proposed in the project is based on logic selectivity and IEC
61850. In addition to alternative network reconfigurations,
DERs and microgrids may be considered to manage service
restoration to minimize outage duration and the number of
affected customers.
Automated protection reconfiguration is needed to optimize protection system performance independently from
the grid or DER configuration. Adaptive protection schemes
enhance the coordination of IEDs and, therefore, the availability of protection systems in complex scenarios. IED
operation parameters will respond to changeable operation
situations, eliminating the need for technical crews to be
dispatched to the installation point and for the protection
system to be interrupted. The use of the IEC 61850 configuration language and the IEC 61850-MMS service for configuration update reduces integration work.
The FLISR solution designed for the IDE4L project is based
on the principle that future secondary substations will be provided with circuit breakers. This will require logic selectivity to
be deployed not only between fault passage indicators but also
among circuit breaker controllers. Considering this, a decentralized approach to be performed by distributed IEDs has been
deployed based on the use of IEC 61850 and the generic objectoriented substation event (GOOSE) communication service,
which is indicated for this kind of application. The application
divides the network operations in three steps:

Reports

Data
Acquisition

State
Estimation

Forecast
Power
Control

SAU
MMS
Control Center-DMS
Substations-
IEDs

DLMS/
COSEM

Prosumers-Smart
Meters and DER IEDs

rfa

pli

Management
CIM
Model
IEC 61850

tio

Bridge
Model

figure 3. An SAU.
46

ieee power & energy magazine

may/june 2017

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - May/June 2017